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Both 99mTc-DTPA and 51Cr-EDTA are widely used to determine glomerular filtration rate (GFR), but few direct comparative studies exist. The shortage of 51Cr-EDTA makes a direct comparison highly relevant. The aim of the study was to investigate if there is any clinically relevant difference between plasma clearance of 99mTc-DTPA and 51Cr-EDTA. Patients ≥18 years of age referred for routine GFR measurement by 51Cr-EDTA were prospectively enrolled. The two tracers (10 MBq 99mTc-DTPA (CaNa3-DTPA) and 2.5 MBq 51Cr-EDTA) were intravenously injected at time zero. A standard 4-sample technique was applied with samples collected at 180, 200, 220 and 240 min, if the estimated GFR (eGFR) was ≥30 mL/min. A comparison of single-sample GFR based on the 200 min sample was also conducted. Fifty-six patients were enrolled in the study. All patients had an estimated GFR >30 mL/min/1.73 m2. No patients suffered from ascites or significant oedema. The mean 51Cr-EDTA plasma clearance was 82 mL/min (range 16-226). The plasma clearances determined by the two methods were highly correlated (r = 0.993). The plasma clearance was significantly higher when measured by 99mTc-DTPA than by 51Cr-EDTA (p = 0.01), but the numerical difference was minimal (mean difference 1.4 mL/min; 95% limits of agreement (LOA) -6.6 to 9.4). The difference between the two methods was independent of the level of renal function. Similar results were found for one-sample GFR. No clinically relevant differences were found between the plasma clearance of 99mTc-DTPA and that of 51Cr-EDTA. Therefore, 99mTc-DTPA can replace 51Cr-EDTA when needed. [ABSTRACT FROM AUTHOR]

Objective. Using a best variable to scale glomerular filtration rate (GFR) is important for clinical practice. The variables, estimated by equations regressed from a healthy population, are usually used in scaling GFR of renal patients. However, because the predicted variables may deviate in renal patients, it is necessary to verify whether these variables can be used to reduce the variability of GFR of renal patients. This study was designed to use repeated measures analyses to identify the best variable for scaling GFR of renal patients. Methods. Patients with non-obstructive renal diseases were enrolled in this study. The absolute GFRs of 99mTc-DTPA renography (gGFR) and plasma clearance (pGFR) were measured. The indices relating to between-subjects variability, such as Passing and Bablok regression, intraclass correlation coefficient (ICC) and concordance correlation coefficient (CCC) were used to identify the best variable from body surface area (BSA), extracellular fluid volume (ECV), lean body mass (LBM), total body water (TBW), body mass index (BMI), and metabolic rate (MR). Results. For the scaled indices related to between-subjects variability, ICC and CCC identified the same ranking sequence (BMI < LBMB(B; Boer) < LBMJ(J; James) < TBW < ECVB(B; Bird) < ECVS(S; Silva) < BSA < MR). In the Passing and Bablok regression, the ratio of residual standard deviation to pooled standard deviation (RSD/PSD) produced the same ranking sequence as that identified by ICC and CCC. Conclusion. The estimated metabolic rate can explain most between-subjects variability of GFR, and seems to be the best variable for scaling GFR of renal patients. [ABSTRACT FROM AUTHOR]

Background and aim. From a clinical point of view determination of glomerular filtration rate (clearance) is important. The aim of the present study was to compare the one-sample clearance to reference multiple-sample 51Cr-EDTA clearance in consecutively referred children suspected of or with established nephro-urological disorders. Material and methods. A total of 75 children, age ½-13 years, received a quantitative intravenous injection of 51Cr-EDTA followed by six plasma samples 10-120 min after injection. The multiple-sample clearance was measured as injected dose relative to the area under the plasma radioactivity curve. The one-sample clearance was determined from a single plasma sample collected at 60, 90 or 120 min after injection according to the one-pool method. Results. The overall accuracy of one-sample clearance was excellent with mean numeric difference to the reference value of 0.7-1.7 mL/min. In 64 children, the one-sample clearance was within ± 4 mL/min of the multiple-sample value. However, in 11 children the numeric difference exceeded 4 mL/min (4.4-19.5). Analysis of age, body size, distribution volume, indicator retention time, clearance level, curve fitting, and sampling time could not explain the observed large difference between one-sample and multiple-sample clearance in these 15% of the children. Conclusion. In the majority of children there is an excellent agreement between one-sample clearance and multiple-sample clearance. However, unexpectedly in a small fraction (15%) larger discrepancies are found. If an accurate clearance value is essential a multiple-sample determination should be performed. [ABSTRACT FROM AUTHOR]

Background . The one-pool or slope-intercept technique is widely used when determining total 51Cr-EDTA plasma clearance (Cl). The one-pool clearance (Cl 1), which always exceeds Cl, has mostly been corrected to Cl by multiplication by a constant factor = 0.80, suggested by Chantler (CH0.80), or by using a second-order polynomial originally proposed by Brøchner-Mortensen (BM) and later recommended by the British Nuclear Medicine Society (BMBNMS). Theoretical considerations indicate that the CH correction gives a systematic overestimate of Cl, whereas the BM correction may underestimate Cl at high values. Objective . To assess the accuracy of Cl as estimated from Cl 1 corrected either by CH0.80 or by second-order polynomials. Material and methods . Clref was determined in 149 subjects (M/F/children: 71/46/32) from a complete plasma curve followed for 4-5 h after injection of 51Cr-EDTA (range of Clref : 8-183 mL/min/1.73 m2). Clest was determined from Cl 1 subsequently corrected by CH0.80 and four second-order polynomials. Results . Using CH0.80 correction, Clest underestimated Clref (by a maximum of 20 %) at Clref values less than about 100 mL/min/1.73 m2 in children and 130 mL/min/1.73 m2 in adults. At higher clearance levels, Clref was increasingly overestimated. Taking the BMBNMS correction as representative of second-order polynomials, Clest increasingly underestimated Clref at high levels, the error being 10 % at a Clref value of about 175 mL/min/1.73 m2. Conclusions. We suggest that the tested correction equations are replaced by the given common correction equation based on the “true” relationship between Cl 1 and Cl thoroughly described in part I of this study. [ABSTRACT FROM AUTHOR]

Background. Total plasma clearance of 51Cr-EDTA, Cl, is widely used as a measure of GFR. Commonly, only the final part of the plasma concentration curve is measured, and a one-pool clearance (slope-intercept clearance), Cl 1, is computed. Empirically determined second-order polynomials of the general form Cl = b⋅Cl 1+c⋅Cl 1 2 are usually used to estimate Cl from a measured Cl 1. However, theoretical considerations indicate that such corrections underestimate Cl at high values. Aims. To derive an analytically correct relationship between Cl and Cl 1 and determine the parameters involved for children and adults. Material and methods. Cl was determined in 149 subjects (M/F/children: 71/46/32) from a complete plasma concentration curve followed for 4-5 h after injection of 51Cr-EDTA (range of clearance: 8-183 mL/min/1.73 m2). Plasma volume, PV and the “missing” area under the plasma fraction curve, a (minutes), not used for determination of Cl 1, were measured. Results. The true relationship between Cl and Cl 1 is given by Cl = Cl 1/(1+f⋅Cl 1), where f = a/PV. For men, women and children alike, the equation f = 0.0032⋅BSA -1.3 was applicable (BSA = body surface area in m2). Estimation errors on clearance were within ±8 % for adults and ±13 % for children (95 % limits of agreement). Conclusions. The true relationship between Cl and Cl 1 of 51Cr-EDTA is given, resulting in a common correction equation applicable for children and adults. The new equation has better mathematical behaviour than quadratic equations on very high values of clearance and takes into account dependence on body size. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the influence of chemically modified β-cyclodextrin (β-CD) which could affect the in-vivo stabilization of liposomal preparation derived from proliposome entrapping inclusion complex of amphotericin B (AmB) with β-CD. A series of liposomal AmB formulations with varying β-CD i.e. Hydroxypropyl β-CD (HPBCD) & Sulfo butyl ether β-CD (SBEBCD) and lipid dose having similar AmB content (0.5 mg/kg) were compared with conventional liposomal amphotericin B (L-AmB) or free AmB in rats and their pharmacokinetic data were analyzed considering the varying volume of distribution with respect to the varying lipid concentration (65mg to 110mg) in blood. These results indicate that L-AmB entrapped inclusion complexes safely achieved higher Cmax (P < 0.05) & AUC (P < 0.02) and demonstrated saturable, nonlinear elimination from plasma via reticuloendothelial organ uptake at higher lipid level (>80mg) as compared with conventional L-AmB or free AmB. Furthermore in-vivo stabilization potential for liposomal preparation via AmB/β-Cyclodextrin inclusion complexes appeared to be in pattern of HPBCD < SBEBCD. It is concluded that the preparation of liposome derived from proliposome entrapping inclusion complex of amphotericinB (AmB) with β-CD could serve an alternative approach to enhance the therapeutic window of AmB in clinical medicine. [ABSTRACT FROM AUTHOR]